JP4729387B2 - Hydraulic control device for belt type continuously variable transmission for vehicle - Google Patents

Description

  The present invention relates to a hydraulic control device for a vehicular belt type continuously variable transmission (CVT) that transmits torque by pressing a belt against a pulley.

  In recent years, there are an increasing number of vehicles equipped with continuously variable transmissions that are highly effective in reducing fuel consumption. In belt-type continuously variable transmissions, belts are wound around primary pulleys and secondary pulleys, and the belts are pressed against both pulleys. Power is transmitted between the belt and each pulley by using friction generated by force. At this time, if the frictional force between the pulley and the belt is smaller than the belt driving force, belt slip may occur and the durability of the continuously variable transmission may be reduced. Therefore, the lower limit value of the oil pressure that gives the pushing force of the pulley, that is, the pulley thrust (hydraulic thrust or simply called thrust) is set so that the frictional force between the pulley and the belt does not fall below the belt driving force. Yes.

However, when reducing the hydraulic pressure to one of the pulleys at the time of gear shifting (during gear ratio control), if the lower limit value is set, the hydraulic pressure cannot be lowered sufficiently and the responsiveness may deteriorate. is there. For this reason, the hydraulic pressure to the other pulley is increased to ensure responsiveness, but the engine load increases with the increase of the hydraulic pressure to the other pulley, resulting in deterioration of fuel consumption.
Therefore, in the prior art, a lower limit value (lower limit guard) is set for the oil pressure to the pulley so that the oil pressure to the low pressure side pulley whose supply oil pressure is low does not fall below this lower limit value, and to the low pressure side pulley. When the hydraulic pressure command value is less than or equal to this lower limit value, by correcting the hydraulic pressure command value to the other high pressure pulley based on the difference between this lower limit value and the hydraulic pressure command value to the low pressure pulley, Shift response is ensured while avoiding belt slip (see, for example, Patent Document 1).

In addition, the low pressure side pulley and the high pressure side pulley in the prior art are determined in advance from the structure of the hydraulic circuit, and generally, the primary hydraulic pressure supplied to the primary pulley uses the secondary hydraulic pressure supplied to the secondary pulley. Therefore, since the primary hydraulic pressure does not exceed the secondary hydraulic pressure, the primary pulley corresponds to the low-pressure pulley and the secondary pulley corresponds to the high-pressure pulley. In this case, the primary hydraulic pressure is guarded by the lower limit value, and when the primary hydraulic pressure command value is equal to or lower than the lower limit value, the secondary hydraulic pressure command value is corrected to the larger side based on the difference between the lower limit value and the primary hydraulic pressure command value. Become.
JP 2001-173770 A

However, in the above prior art, when controlling the gear ratio, focusing on the hydraulic pressure, the lower limit guard prevents the belt slip while ensuring the shift response. However, depending on the shift condition, it may be necessary. There is still room for improvement in fuel consumption, not the minimum hydraulic pressure supply.
That is, in the above-described conventional technology, for example, when the up-shift is performed in a region where the pulley thrust of the primary pulley is smaller than the pulley thrust of the secondary pulley, the thrust command value of the secondary pulley that holds a high thrust remains high, This is dealt with by increasing the thrust command value of the primary pulley that holds the low thrust, which requires a high hydraulic pressure as a whole, leaving room for improving fuel efficiency (see FIG. 8).

Also, when downshifting is performed in a region where the pulley thrust of the primary pulley is larger than the pulley thrust of the secondary pulley, the thrust command value of the primary pulley that retains high thrust remains high, and the secondary thrust that retains even lower thrust. In order to increase the thrust command value of the pulley, there is a problem similar to the above (see FIG. 10).
In the prior art, even when attention is paid to the pulley stroke error e (difference between the actual stroke x and the target stroke x *; e = x * −x) when controlling the gear ratio, the stroke error e As for the pulley control input, the control correction up to the change of thrust ratio RF (ratio of primary pulley thrust Fpri and secondary pulley thrust Fsec; RF = Fpri / Fsec) has not been made. Therefore, the feedback control input is relatively small in the low gear ratio region where the pulley thrust is high, and the feedback control input is relatively large in the high gear ratio region where the pulley thrust is low. I was invited.

In addition, at the time of shifting, it is desired to change the shifting speed, that is, the stroke speed of each pulley according to the differential thrust, but the conventional technology does not have a logic to properly associate the stroke speed and the differential thrust, which is a problem. Yes.
The present invention has been devised in view of such problems, and is a vehicle continuously variable transmission that can improve both responsiveness and fuel efficiency while paying attention to the thrust ratio of both pulleys. An object is to provide a hydraulic control device.

In order to achieve the above-described target, the hydraulic control device for a continuously variable transmission for a vehicle according to the present invention connects the driving pulley and the driven pulley with a belt, and adjusts the hydraulic thrust applied to both the pulleys. A hydraulic control device for a belt-type continuously variable transmission for a vehicle that adjusts a gear ratio by changing a rotation radius of the belt in the pulley, wherein the rotation of the driving pulley and the driven pulley according to the hydraulic thrust Based on a hydraulic actuator that changes the radius, vehicle information detection means for detecting vehicle information, and vehicle information detected by the vehicle information detection means, the hydraulic thrust for the drive pulley and the driven pulley is calculated. And a control unit for controlling the hydraulic actuator based on the calculated value, the control unit comprising the vehicle information A target gear ratio is calculated on the basis of the above, a thrust ratio that is a ratio of a hydraulic thrust force to the driving pulley and a hydraulic thrust force to the driven pulley for maintaining the target gear ratio is calculated; A drive side slip lower limit value and a drive side slip lower limit value, which are lower limit values of hydraulic thrust at which the belt does not slip with respect to rotation of the driven pulley, are calculated, and when the thrust ratio is less than 1, the drive side slip lower limit value Is set to the first drive-side target hydraulic thrust that is the target hydraulic thrust of the drive-side pulley, and the target hydraulic thrust of the driven-side pulley is set based on the drive-side slip lower limit value and the target gear ratio. 1 driven side target hydraulic thrust is calculated, and when the thrust ratio is 1 or more, the driven side slip lower limit value is set to a second driven side target hydraulic thrust that is a target hydraulic thrust of the driven pulley, and Under driven side slip Calculates the second drive-side target hydraulic thrust, which is a target hydraulic thrust of the drive pulley on the basis of said value target gear ratio, further wherein when the hydraulic thrust ratio is less than 1, maintaining the target gear ratio A value obtained by adding or subtracting a control thrust amount necessary for gear shifting to the driven side basic balance thrust, which is the hydraulic thrust of the driven pulley to perform, is calculated as a candidate value of the first driven target hydraulic thrust, and the driven slip A lower limit value is compared with the first driven side target hydraulic thrust candidate value, and if the first driven side target hydraulic thrust candidate value is larger than the driven side slip lower limit value, the first driven side target hydraulic thrust candidate value Is the first driven-side target hydraulic thrust, and the driven-side slip lower limit value is larger than the first driven-side target hydraulic thrust candidate value, the driven-side slip lower limit value and the first driven-side target hydraulic thrust candidate value Is the difference between A driven-side differential value is calculated, and the sum of the drive-side slip lower limit value and the driven-side differential value is used as the first drive-side target hydraulic pressure thrust, and the driven-side slip lower limit value is used as the first driven-side target hydraulic pressure. When the hydraulic thrust ratio is 1 or more, a value obtained by adding / subtracting the control thrust required for shifting to the driving basic balance thrust, which is the hydraulic thrust of the driving pulley for maintaining the target speed ratio Is calculated as a candidate value for the second drive side target hydraulic thrust, the drive side slip lower limit value is compared with the second drive side target hydraulic thrust candidate value, and the second drive side target hydraulic thrust candidate value is When it is larger than the drive side slip lower limit value, the second drive side target hydraulic thrust candidate value is set as the second drive side target hydraulic pressure, and the drive side slip lower limit value is larger than the second drive side target hydraulic thrust candidate value. The drive side A drive side differential value, which is a difference between a lower limit value and the second drive side target hydraulic thrust candidate value, is calculated, the drive side slip lower limit value is set as the second drive side target hydraulic thrust, and the driven side slip lower limit is set. The sum of the value and the drive-side differential value is used as the second driven-side target hydraulic thrust (claim 1).

The vehicle information detecting means, an engine rotation sensor, the drive-side rotation sensor, the driven-side rotation sensor, a throttle opening sensor, and preferably a vehicle speed sensor (claim 2).
Further, the control unit calculates a differential thrust, which is a difference between a hydraulic thrust for the driving pulley and a hydraulic thrust for the driven pulley, to obtain a target transmission speed, and sets an actual transmission ratio to the target transmission ratio. In order to follow, a stroke difference value that is a difference between a target stroke displacement of the driven pulley calculated from the target gear ratio and an actual stroke displacement of the driven pulley calculated from the actual gear ratio, and feedback control Based on the gain, a feedback control amount applied to the hydraulic thrust is calculated, and the first or second drive-side target hydraulic thrust and the first or second driven-side target hydraulic thrust are calculated from the differential thrust and the feedback control. based on the hydraulic thrust corrected by the amount, it is preferable to control the hydraulic actuator (claim 3).

Further, the control unit calculates a correction value for equalizing the rate of change of the thrust ratio based on the driving-side slip lower limit value and the driven-side slip lower limit value, and the feedback control amount is calculated based on the correction value. on corrected, or controlling the hydraulic actuator, or on the said feedback control amount and said difference thrust corrected respectively by the correction value, it is preferable to control the hydraulic actuator (claim 4 , 5 ).

In this case, the correction value for equalizing the rate of change of the thrust ratio is such that the driving side basic balance thrust and the driving side basic balance thrust match the driving side sliding lower limit value and the driven side sliding lower limit value. It is preferable to make the dimensionless by using the hydraulic thrust between the slip lower limit values with a gear ratio of 1 at which the stroke displacement of each pulley is neutral from the hydraulic thrust (Claim 6 ).

According to the hydraulic control device for a continuously variable transmission for a vehicle according to the present invention (Claim 1), it is possible to prevent the belt from slipping while lowering the operating hydraulic pressure, and to improve both responsiveness and fuel efficiency improvement. It becomes like this.
According to the hydraulic control device for a continuously variable transmission for a vehicle according to the present invention (claim 1 ), the shift speed can be increased, and good responsiveness of the shift control can be ensured.

According to the hydraulic control device for a continuously variable transmission for a vehicle according to the present invention (claims 3 to 6 ), it is possible to improve the stability of control by assigning roles to each control parameter at the time of shift control.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Embodiment]
FIGS. 1 to 11 illustrate an embodiment of the present invention. FIGS. 1 and 2 are diagrams illustrating the configuration, FIGS. 3 to 5 are various correlation diagrams illustrating the control contents, and FIGS. FIG. 7 is a flowchart for explaining the control contents, and FIGS. 8 to 11 are diagrams for explaining the effects.

[System configuration of vehicle equipped with CVT hydraulic control device]
FIG. 1 is a system configuration diagram of a vehicle (automobile) equipped with a CVT hydraulic control device (hydraulic control device for a continuously variable transmission for a vehicle). The power of the engine 10 is transmitted to the CVT 300 via the torque converter 20 and the forward / reverse clutch 30. The CVT 300 includes a primary pulley 310 on the driving side and a secondary pulley 320 on the driven side, and transmits power by a belt 330 interposed therebetween.

  In the CVT 300, the oil pressure applied to the pulleys 310 and 320 on both the driving side and the driven side is controlled independently, so that the primary pulley (driving pulley) 310 and the secondary pulley (driven pulley) 320 are Each includes a primary slide pulley 311 and a secondary slide pulley 321. The primary slide pulley 311 and the secondary slide pulley 321 are slid by hydraulic pressure to change the belt rotation radii in the primary pulley 310 and the secondary pulley 320 independently, thereby performing a shift.

  The oil pump 40 supplies oil to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72 via the first pressure regulating valve 51 and supplies oil to the primary solenoid 108 and the secondary solenoid 109 via the second pressure regulating valve 52. It is. Further, the primary solenoid 108 and the secondary solenoid 109 are solenoid valves controlled by the CVT control unit 100, and control is performed by connecting to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72, respectively, and sending a signal pressure.

[Hydraulic control of CVT pulley]
The hydraulic pressure generated by the oil pump 40 is adjusted to the line pressure by the first pressure regulating valve 51 and supplied to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72. Further, the pilot pressure is set by the second pressure regulating valve 52 and supplied to the primary solenoid 108 and the secondary solenoid 109. The CVT control unit 100 controls the primary solenoid 108 and the secondary solenoid 109, adjusts the supplied pilot pressure to a desired signal pressure, and supplies it to the primary pressure regulating valve 71 and the secondary pressure regulating valve 72.

  The primary pressure adjustment valve 71 and the secondary pressure adjustment valve 72 adjust the line pressure based on the supplied signal pressure, and supply the oil pressure to the primary slide pulley 311 and the secondary slide pulley 321 to slide them. As described above, the CVT control unit 100 controls the primary solenoid 108 and the secondary solenoid 109 to achieve shifting of the CVT 300.

[Control configuration of CVT control unit]
FIG. 2 is a control block diagram of the CVT control unit 100. The CVT control unit 100 includes a transmission ratio control unit 200, a hydraulic pressure conversion unit 106, and a current conversion unit 107. The transmission ratio control unit 200 further includes a target transmission ratio calculation unit 201, an actual transmission ratio calculation unit 202, Input torque calculator 203, slip lower limit thrust calculator 204, thrust ratio calculator 205, basic balance thrust calculator 206, differential thrust calculator 207, correction value calculator 208, shift feedback controller (shift feedback amount calculator) 209 , Anti-slip and hydraulic minimum thrust distribution calculation unit (hereinafter referred to as thrust distribution calculation unit) 210.

  Further, in a vehicle equipped with the hydraulic control device for the belt type continuously variable transmission, the vehicle speed sensor 101, the primary rotation sensor 102 that detects the rotation speed of the primary pulley 310, and the secondary rotation sensor that detects the rotation speed of the secondary pulley 320. 103, an engine rotation sensor 104, and a throttle opening sensor 105, each of which outputs a detection value to the gear ratio control unit 200 of the CVT control unit 100.

The target gear ratio calculation unit 201 is based on the vehicle speed VSP input from the vehicle speed sensor 101, the primary pulley rotation speed Npri input from the primary rotation sensor 102, and the throttle opening TV0 input from the throttle opening sensor 105. * Is calculated and output to the differential thrust calculation unit 207 and the shift feedback control unit 209.
The actual gear ratio calculation unit 202 calculates the actual gear ratio ip based on the primary pulley rotation speed Npri and the secondary pulley rotation speed Nsec input from the primary and secondary rotation sensors 210 and 220, and the slip lower limit thrust calculation unit 204, thrust ratio The result is output to the calculation unit 205, the differential thrust calculation unit 207, the correction value calculation unit 208, and the shift feedback control unit 209.

  The input torque calculation unit 203 receives inputs of the engine rotation speed Ne, the primary pulley rotation speed Npri, and the throttle opening TV0 from the engine rotation sensor 104, the primary rotation sensor 102, and the throttle opening sensor 105, and receives the primary pulley rotation speed NPri and the engine. The speed ratio VS is calculated based on the rotational speed Ne, and the engine torque Te is calculated based on the throttle opening TV0 and the engine rotational speed Ne. The input torque Tin to the primary pulley 310 is calculated from the speed ratio VS, the engine speed Ne, and the engine torque Te, and is output to the slip lower limit thrust calculation unit 204 and the thrust ratio calculation unit 205.

The lower slip thrust calculating unit 204 calculates lower slip thrusts Flp and Fls in the primary pulley 310 and the secondary pulley 320 based on the actual gear ratio ip and the input torque Tin input from the actual gear ratio calculating unit 202 and the input torque calculating unit 203. And output to the basic balance thrust calculation unit 206 and the correction value calculation unit 208.
Here, the slip lower limit thrusts Flp and Fls are the thrusts of the pulleys capable of transmitting torque between the pulleys and the belt without causing belt slip. Specifically, if the transmission torque and belt rotation radius in the primary pulley 310 are Tpri, Rpri, the narrow angle of the pulley is θ, and the dynamic friction coefficient between the pulley and the belt is μ, the transmission torque Tpri of the primary pulley 310 is
Tpri = Rpri × 2μ × Fpri / cos θ
That is,
Fpri = Tpri × cos θ / (2 μ × Rpri)
The conditions under which no belt slip occurs in the primary pulley 310 are as follows:
Since the frictional force between the pulley and the belt is equal to or greater than the transmission torque, if the safety factor is εpri, the lower limit thrust Flp in the primary pulley 310 is
Flp = εpri × Tpri × cos θ / (2 μ × Rpri)
On the other hand, the slip lower limit thrust Fls in the secondary pulley 320 is also obtained in the same manner as in the primary pulley 310.
Fls = εsec × Tsec × cos θ / (2 μ × Rsec)
Here, since the belt tension T in the primary pulley 310 and the secondary pulley 320 is the same,
T = Tpri / Rpri = Tsec / Rsec
Therefore,
Tsec = Tpri × Rsec / Rpri
Therefore, Fls = εsec × (Tpri × Rsec / Rpri) × cos θ / (2 μ × Rsec)
= Εsec × Tpri × cos θ / (2 μ × Rpri)
= (Εsec / εpri) Flp
If the safety factor on the primary side and the secondary side are the same, Flp = Fls = F
Thus, the slip lower limit thrust Flp of the primary pulley 310 and the slip lower limit thrust Fls of the secondary pulley 320 have the same value F.

In the thrust ratio calculation unit 205, based on the actual transmission ratio ip input from the actual transmission ratio calculation unit 202 and the input torque Tin input from the input torque calculation unit 203, a thrust ratio RF ( = Fp / Fs, Fp: primary thrust, Fs: secondary thrust) are calculated and output to the calculation unit 206 and the thrust distribution calculation unit 210.
The basic balance thrust calculation unit 206 is configured to use the primary pulley 310 and the secondary pulley 320 based on the slip lower limit thrusts Flp and Fls input from the slip lower limit thrust calculation unit 204 and the thrust ratio RF input from the thrust ratio calculation unit 205. The basic balance thrusts Fp * and Fs * are calculated and output to the thrust distribution calculation unit 210.

  The calculation of the basic balance thrusts Fp * and Fs * will be described. As shown in FIG. 3A, the thrust F tends to increase as the gear ratio ip increases (lower), and increases as the input torque Tin increases. A characteristic line of Flim (see a thick line in FIG. 3A) can be set. Further, as shown in FIG. 3B, the thrust ratio RF tends to be lower as the gear ratio ip is higher (lower side), and higher as the transmission torque is higher. When the transmission torque is 0 (none) At the time of driving), the thrust ratio = 1 when the transmission ratio = 1, but at the time of downhill driving where the transmission ratio becomes positive and the transmission ratio becomes negative when the transmission torque becomes positive. During coasting, the thrust ratio = 1 when the gear ratio <1.

  As for the basic balance thrust, in the region where the thrust ratio RF is RF <1, the basic balance thrust Fp * of the primary pulley is set to the value of the lower limit thrust Flim, and the basic balance thrust Fs * of the secondary pulley is the basic balance thrust of the primary pulley. Fp *, that is, a thrust value that is higher than the slip lower limit thrust Flim by a value equivalent to the reciprocal of the thrust ratio (1 / RF) is set. In the region where the thrust ratio is greater than 1, the basic balance thrust Fs * of the secondary pulley is set to the value of the lower limit thrust Flim, and the basic balance thrust Fp * of the primary pulley is the basic balance thrust Fs * of the secondary pulley, that is, the lower limit thrust. The thrust value is set to a value equivalent to the thrust ratio RF higher than Flim.

  If such a basic balance thrust is shown in correspondence with the gear ratio ip, as shown in FIG. 3C, the thrust ratio of gear ratio <1 = 1 at the time of creep travel or coast travel where the transmission torque is negative. When the thrust ratio <1 and the thrust ratio> 1 are divided, the basic balance thrusts Fp * 1 and Fs * 1 are determined, and the transmission torque is 0 (no load), the gear ratio = 1 Centered on the thrust ratio = 1, the thrust ratio <1 and the thrust ratio> 1 are divided into regions, the basic balance thrusts Fp * 2 and Fs * 2 are determined, and the drive ratio when the transmission torque is positive, the gear ratio> Centering on the thrust ratio = 1 = 1, the thrust ratio <1 and the thrust ratio> 1 are divided into regions, and the basic balance thrusts Fp * 3 and Fs * 3 are determined.

  Thus, when there is no load, as shown in FIG. 4A, the thrust ratio = 1 when the gear ratio = 1, and the basic balance thrusts Fp * and Fs * can be set with the gear ratio = 1 as a boundary. However, when there is a load, as shown in FIG. 4 (b), the thrust ratio = 1 when the gear ratio> 1, or the thrust ratio = 1 when the gear ratio <1, so that the basic balance thrust Fp * , Fs *, it is important to focus on the thrust ratio RF.

  Then, as shown in FIG. 5, in a region where the thrust ratio = 1, where the gear ratio is larger than that at the thrust ratio = 1, the basic balance thrust Fp * of the primary pulley is set as the lower limit thrust Flim, A secondary control region in which the basic balance thrust Fs * of the secondary pulley is set according to the required thrust ratio, and in the region where the thrust ratio is smaller than the thrust ratio = 1, the basic balance of the secondary pulley. The thrust Fs * is defined as a primary control region in which the basic balance thrust Fp * of the primary pulley is set according to the required thrust ratio as the lower limit thrust Flim.

  The differential thrust calculator 207 calculates a differential thrust dF for obtaining a target shift speed until the target gear ratio is reached, from the relationship between the differential thrust and the shift speed (or stroke speed). The differential thrust dF is calculated from the difference between the target speed ratio ip * and the actual speed ratio ip.

The correction value calculation unit 208 calculates a shift control input correction value α suitable for the driving condition VSP and the gear ratio. This correction value α is for equalizing the change rate of the thrust ratio, and is calculated from the following equation.
α = Flim / Fo
Flim: slip lower limit thrust for each ip, Fo: variable for making α non-dimensional (slip lower limit thrust with gear ratio ip = 1 to thrust ratio RF = 1)
The shift feedback control unit 209 sets the feedback control amount Ufb so that the actual gear ratio reliably follows the target shift. This feedback control amount Ufb is obtained from the following equation.
Ufb = K _P · e + K _I ∫edt + K _D · de / dt
e = x _SA -x _SR
Where e: Stroke error, x _SA : Target secondary stroke, x _SR : Actual secondary stroke, K _P : Proportional gain, K _I : Integration gain, K _D : Differential gain

  The thrust distribution calculating unit 210 includes a basic balance thrust calculating unit 206, a differential thrust calculating unit 207, a correction value calculating unit 208, and a basic balance thrust Fp *, Fs *, a differential thrust dF input from the shift feedback control unit 209, and a correction. Based on the value α and the feedback control amount Ufb, the primary thrust command value Fpri and the secondary thrust command value Fsec are calculated and output to the hydraulic pressure conversion unit 106.

  That is, the thrust distribution calculation unit 210 determines whether or not the thrust ratio is 1 or less. If the thrust ratio is 1 or less, the primary thrust command value Fpri is set as the primary thrust lower limit value Flp (Fpri = Fp * = Flp), and the secondary The thrust command value Fsec is the basic balance thrust Fs * plus the differential thrust dF and the F / B control amount (Fsec = Fs * + Uin, where Uin = dF + α · Ufb or Uin = α · (dF + Ufb) ).

  Further, it is determined whether the secondary thrust is smaller than the secondary slip lower limit value Fls while the thrust ratio is 1 or less. If the secondary thrust is smaller than the secondary slip lower limit value Fls, the secondary thrust Fsec and the slip lower limit value Fls Is calculated (ΔFs = Fls−Fsec), the primary thrust is changed to Flp + ΔFs (Fpri = F1p + ΔFs), and the secondary thrust is changed to Fls (Fsec = Fls).

  On the other hand, if the thrust ratio is greater than 1, the primary thrust command value Fpri (Fpri = Fp * + Uin) is obtained by adding the differential thrust and the F / B control amount to the primary side, and the secondary thrust command value Fsec is the secondary thrust lower limit. The value Fls is assumed (Fsec = Fs * = Fls, where Uin = dF + α · Ufb or Uin = α · (dF + Ufb)).

  Further, it is determined whether the primary thrust is smaller than the primary slip lower limit F1p while the thrust ratio is larger than 1. If the primary thrust is smaller than the primary slip lower limit F1p, the primary thrust Fpri and the slip lower limit are determined. The difference from Flp is calculated (ΔFp = F1p−Fpri), the primary thrust is changed to the primary thrust lower limit Flp and Fpri = Flp), and the secondary thrust is changed to Flp + ΔFs (Fsec = Fls + ΔFp).

The hydraulic pressure conversion unit 106 converts the input thrust command values Fpri and Fsec into hydraulic command values Ppri and Psec. In the primary pulley 310 and the secondary pulley 320, the thrust command values Fpri and Fsec are corrected in consideration of the difference in the hydraulic pressure change amount due to centrifugal force, the pulley holding spring force, and the pressure receiving area, and the hydraulic command values Ppri and Psec are corrected. Converted and output to the current converter 107.
The current converter 107 converts the input hydraulic pressure command values Ppri and Psec into control currents for the solenoids, and outputs current values.

[Pulley thrust calculation control processing]
FIG. 6 is a flowchart showing a flow of pulley thrust calculation control processing executed in the CVT control unit 100. Hereinafter, each step will be described.

In step S1, the detected values of the vehicle speed sensor 101, primary rotation sensor 102, secondary rotation sensor 103, engine rotation sensor 104, and throttle opening sensor 105 are read, and the process proceeds to step S2.
In step S2, the actual speed ratio ip, the target speed ratio ip *, and the input torque Tin are calculated in the target speed ratio calculating unit 201, the actual speed ratio calculating unit 202, and the input torque calculating unit 203, and the process proceeds to step S3.

In step S3, the slip lower limit thrust calculation unit 204 calculates slip lower limit thrusts Flp and Fls that prevent the belt from slipping from the actual gear ratio and the primary input torque, and proceeds to step S4.
In step S4, the thrust ratio calculation unit 205 calculates a thrust ratio RF that can maintain a predetermined gear ratio from the running condition and the input torque, and the process proceeds to step S5.

In step S5, the basic balance thrust calculation unit 206 calculates the basic balance thrust Fp * and Fs * based on the actual speed ratio ip, the target speed ratio ip * and the input torque Tin calculated in step S2, and then goes to step S6. Transition.
In step S6, the differential thrust calculation unit 207 obtains a target shift speed to be added to the balance thrust between the primary pulley 310 and the secondary pulley 320 based on the target speed ratio ip * and the actual speed ratio ip calculated in step S2. The differential thrust dF (Fp * −Fs *) is calculated, and the process proceeds to step S7.

In step S7, the correction value calculation unit 208 calculates the correction value α of the gear ratio F / B control suitable for the driving condition and the gear ratio, and the process proceeds to step S8.
In step S8, the shift feedback control unit 209 calculates shift feedback control Ufb so that the actual shift ratio reliably follows the target shift, and the process proceeds to step S9.

  In steps S9 to S17, in the thrust distribution calculation unit 210, the basic balance thrusts Fp * and Fs input from the basic balance thrust calculation unit 206, the differential thrust calculation unit 207, the correction value calculation unit 208, and the shift feedback control unit 209, respectively. * Based on the differential thrust dF, the correction value α, and the feedback control amount Ufb, the primary thrust command value Fpri and the secondary thrust command value Fsec are calculated.

That is, step S9 determines whether the thrust ratio is 1 or less.
If it is determined in step S9 that the thrust ratio is 1 or less, the process proceeds to step S10, where the primary thrust is set to the primary thrust lower limit (Flp) (Fpri = Fp * = Flp), and the differential thrust and F / B are set to the secondary side. The control amount is added (Fsec = Fs * + Uin, Uin = dF + α · Ufb or Uin = α · (dF + Ufb)), and the process proceeds to step S11.

In step S11, it is determined whether the secondary thrust is smaller than the secondary slip lower limit Fls obtained in step S3.
If it is determined in step S12 that the secondary thrust is smaller than the secondary slip lower limit value Fls, the process proceeds to step S12 to calculate how much the secondary thrust Fsec falls below the slip lower limit value Fls (ΔFs = Fls−Fsec). The process proceeds to step S13.
In step S13, the new primary thrust is set to Flp + ΔFs (Fpri = F1p + ΔFs), and the new secondary thrust is set to Flb (Fsec = Fls).

On the other hand, if it is determined in step S9 that the thrust ratio is greater than 1, the process proceeds to step S14. In step S14, the differential thrust and the F / B control amount are added to the primary side (Fpri = Fp * + Uin, Uin = dF + α · Ufb or Uin = α · (dF + Ufb)), the secondary thrust is set to the secondary thrust lower limit (Fls) (Fsec = Fs * = F1s), and the process proceeds to step S15.
In step S15, it is determined whether the primary thrust is smaller than the primary slip lower limit F1p obtained in step S3.

If it is determined in step S15 that the primary thrust is smaller than the primary slip lower limit value F1p, the process proceeds to step S16. In step S16, how much the primary thrust Fpri is lower than the slip lower limit value Flp is calculated (ΔFp = F1p). -Fpri), the process proceeds to step S17.
In step S17, the new primary thrust is set as the primary thrust lower limit (Flp) (Fpri = Flp), and the new secondary thrust is set as Fls + ΔFp (Fsec = Fls + ΔFp).

[Hydraulic conversion control processing]
FIG. 7 is a flowchart showing the flow of the hydraulic pressure conversion control process executed by the hydraulic pressure conversion unit 106 of the CVT control unit 100 as the process after step S13 or S17 shown in FIG. Hereinafter, each step will be described.

In step S21, the target hydraulic pressure command values P * pri and P * sec for each pulley are obtained from the conditions of the amount of change in hydraulic pressure due to the centrifugal force generated as each pulley rotates, the spring force holding each pulley, and the pressure receiving area. The calculation is performed and the process proceeds to step S22.
In step S22, the minimum hydraulic pressure command values Ppri_min and Psec_min in each pulley are calculated from each condition, and the process proceeds to step S23.

In step S23, it is determined whether the calculated target hydraulic pressure command value P * pri or P * sec is lower than the minimum hydraulic pressure command value Ppri_min or Psec_min. If YES, the process proceeds to step S24, and if NO, control is performed. finish.
In step S24, the differences Ppri_min−P * pri and Psec_min−P * sec between the minimum hydraulic pressure command values Ppri_min and Psec_min and the target hydraulic pressure command values P * pri and P * sec are calculated, and the primary side difference Ppri_min−P * pri = a (Pri), secondary side difference Psec_min−P * sec = a (sec), and the process proceeds to step S25.

In step S25, the values of a (pri) and a (sec) calculated in consideration of the difference in pressure receiving area between the primary pulley 310 and the secondary pulley 320 are corrected, and a (Pri) ′ and a (sec) ′ are corrected. As shown in FIG.
In step S26, the correction amount a (Pri) ′ or a (sec) ′ calculated in step S25 is added to the hydraulic pressure command value for the pulley that is not below the minimum hydraulic pressure, and the control is terminated.

[Contrast of prior art and this embodiment]
[1-1: Comparison of transmission ratio-thrust correlation diagram in a region where the thrust ratio is less than 1]
FIG. 8 is a diagram showing a comparison between the prior art in the region where the thrust ratio is less than 1 (the region on the low side where the gear ratio is larger than the thrust ratio 1) and the gear ratio-thrust correlation diagram in the present embodiment. FIG. 8A shows a gear ratio-thrust correlation diagram of the prior art, and FIG. 8B shows a gear ratio-thrust correlation diagram of pulley thrust control by the hydraulic control device of the belt type continuously variable transmission of the present application.

  In the prior art, a lower limit is set for the pulley thrust to avoid belt slip, and control is performed to ensure a differential thrust corresponding to the target gear ratio by increasing / decreasing the thrust of the low thrust pulley during gear shifting. When the thrust command value on the low output side falls below the lower limit thrust, the lower limit thrust is maintained. Also, in order to avoid the deterioration of the responsiveness by reducing the time change rate of the belt rotation radius of the pulley having a low thrust by holding, the difference between the thrust command value on the low output side and the lower limit thrust is taken, and this The difference is added to the thrust command value of the pulley with high thrust to ensure responsiveness.

  On the other hand, in this embodiment, the thrust of the low thrust side pulley is held at the slip limit thrust, and the thrust of the high thrust side pulley is increased / decreased to perform control to ensure the differential thrust corresponding to the target gear ratio. When the thrust command value on the high thrust side falls below the lower limit thrust, the thrust command value on the high thrust side is held at the lower limit thrust. Further, in order to ensure responsiveness, the difference between the thrust command value on the high thrust side and the lower limit thrust is taken, and this difference is added to the thrust command value of the low thrust side pulley.

(Downshift in areas where the thrust ratio is less than 1)
When downshifting is performed by increasing the gear ratio from β1 to β2, it is necessary to reduce the belt rotation radius of the primary pulley and increase the belt rotation radius of the secondary pulley. In this case, in the prior art, in order to reduce the primary thrust to reduce the belt rotation radius of the primary pulley on the low thrust side, an attempt is made to reduce the primary thrust to achieve speed change, but the primary thrust corresponding to the target speed ratio β2 does not slip. Since the value falls below the lower limit, a difference B between the target primary thrust and the slip lower limit is calculated, and this difference B is added to the secondary thrust on the high thrust side. Similarly, in the present embodiment, since the primary thrust on the low thrust side is held at the slip lower limit thrust, the secondary thrust F * sec is increased in order to increase the belt rotation radius of the secondary pulley 320.
Therefore, in the downshift in the region where the thrust ratio is less than 1, both the conventional technology and the present embodiment maintain the primary thrust at the slip lower limit thrust and secure the differential thrust corresponding to the target gear ratio by increasing the secondary thrust. Downshift. As a result, both increase the hydraulic pressure.

(Upshift in the area where the thrust ratio is less than 1)
When performing an upshift by reducing the gear ratio from β1 to β3, it is necessary to increase the belt rotation radius of the primary pulley and reduce the belt rotation radius of the secondary pulley. In this case, in the prior art, in order to achieve the upshift by expanding the belt rotation radius of the primary pulley on the low thrust side, the primary thrust is increased to ensure the differential thrust corresponding to the target gear ratio, Achieve shifts. At this time, since the secondary thrust on the high thrust side remains high, the primary thrust and the secondary thrust are both kept high, and the hydraulic load is high as a whole.

  In the present embodiment, in order to achieve the upshift by reducing the belt rotation radius in the secondary pulley 320 on the high thrust side, the secondary thrust F * sec is decreased to ensure the differential thrust corresponding to the target gear ratio. At this time, when the value of the target secondary thrust F * sec falls below the slip lower limit value of the pulley thrust, the secondary thrust command value Fsec is held at the slip lower limit value, and the difference value ΔFs between the slip limit value and the target secondary thrust F * sec. And the difference value ΔFs is added to the primary thrust command value Fpri.

  Therefore, in the upshift in the region where the gear ratio is 1 or more, in the prior art, the hydraulic load increases because both the primary thrust and the secondary thrust are kept high, but in the present embodiment, the secondary thrust command of the high thrust is high. The hydraulic load is reduced by lowering the value Fsec. Further, when the value of the target secondary thrust F * sec falls below the slipping lower limit value of the pulley thrust, the secondary thrust command value Fsec is held at the slipping lower limit value, and the difference value ΔFs between the slipping lower limit value and the target secondary thrust F * sec. And the difference value ΔFs is added to the primary thrust command value Fpri to ensure responsiveness.

[1-2: Contrast of change with time in the region where the thrust ratio is less than 1]
FIG. 9 is a time chart showing changes with time of each pulley thrust force in the prior art and in the present embodiment when upshifting is performed in a region where the thrust ratio RF is less than 1. FIG. 9A shows a time chart of the prior art, and FIG. 9B shows a time chart of pulley thrust control by the hydraulic control device of the belt type continuously variable transmission of the present application.

(Time t1)
Upshift transmission control is started at time t1. In the prior art, the primary thrust command value is controlled to increase the pulley thrust on the low thrust side to ensure the differential thrust corresponding to the target gear ratio, but in this embodiment the thrust command value for the high thrust pulley is decreased. To ensure a differential thrust corresponding to the target gear ratio. Therefore, in the prior art, the primary thrust command value Fpri rapidly increases and the secondary thrust command value Fsec gradually decreases so that the belt rotation radius of each pulley is set to the rotation radius corresponding to the target speed ratio ip *.

On the other hand, in the present embodiment, the thrust command value Fsec of the secondary pulley 320 to which high hydraulic pressure is applied is controlled to reach the target speed ratio ip *, so that the thrust command value Fpri of the primary pulley 310 is set to the slip lower limit thrust Flp. While holding, the value of the thrust command value Fsec of the secondary pulley 320 is decreased to perform upshift.
At this time, the thrust command value Fsec of the secondary pulley 320 rapidly decreases to correspond to the target gear ratio ip *, and accordingly, the difference in thrust between the primary pulley 310 and the secondary pulley 320 decreases rapidly. Fsec falls below the lower slip limit thrust Fls and tries to further decrease. However, the shift control unit 160 sets the lower limit of the slip lower limit thrust Fls to Fsec, reaches the slip lower limit thrust Fls, and stops decreasing.

(Time t1 to t2)
From time t1 to t2, the secondary thrust in the conventional technique continues to decrease, and the primary thrust slightly decreases although the control amount changes at the same value.
On the other hand, in this embodiment, when the thrust command value Fsec of the secondary pulley 320 reaches the slip lower limit thrust Fls and stops decreasing, the time change rate of the belt rotation radius of the secondary pulley 320 decreases, and the primary thrust command value If Fpri is kept at the sliding lower limit thrust Flp, the responsiveness deteriorates.

  Therefore, the difference ΔFs between the lower limit sliding slip Fls and the secondary thrust command value Fsec is added to the primary thrust command value Fpri. By adding ΔFs, the value of Fpri starts to rise and continues to rise from time t1 to time t2. Further, the secondary thrust command value Fsec is maintained as it is by the slip limit thrust. The differential thrust between the secondary thrust command value Fsec and the primary thrust command value Fpri also changes at the same value as t1.

(Time t2)
At time t2, the primary thrust starts to decrease rapidly in the prior art, and the control amount to the primary pulley also starts to decrease accordingly. In the present embodiment, when it is assumed that the secondary thrust command value Fsec has not stopped even if the secondary thrust command value Fsec reaches the slip lower limit thrust, Fsec reaches the thrust command value Fsec and starts increasing at time t2. Therefore, the difference ΔFs between the lower limit thrust and the secondary thrust command value Fsec starts to decrease, and the primary thrust Fpri added with ΔFs also starts to decrease. As Fpri decreases, the differential thrust begins to decrease.

(Time t3)
At time t3, the value of the difference ΔFs between the lower slip thrust Fls and the secondary thrust command value Fsec becomes zero. Therefore, the flow of control proceeds from step S13 or S17 in the flowchart of FIG. 6 to step S20 in the flowchart of FIG. 7, the primary thrust command value Fpri is held at the slip limit thrust value, and the secondary thrust command value Fsec is the target gear ratio. The belt rotation radius corresponding to ip * is controlled to start rising.

(Time t4)
At time t4, both the belt rotation radius of the conventional technology and this embodiment reach a value corresponding to the target speed ratio ip *, and each pulley thrust becomes a constant value. Accordingly, in the conventional technique, the control amount of the primary pulley becomes a constant value, and in this embodiment, the differential thrust becomes zero.

[2-1: Comparison of thrust correlation diagram with gear ratio in region where thrust ratio is 1 or more]
FIG. 10 is a diagram showing a comparison between the prior art in a region where the thrust ratio is 1 or more (a region on the high side where the gear ratio is smaller than the thrust ratio 1) and the gear ratio-thrust correlation diagram in the present embodiment. FIG. 10 (a) shows a correlation diagram of thrust against the gear ratio of the prior art, and FIG. 10 (b) shows a gear ratio-thrust correlation diagram of pulley standard force control by the hydraulic control device of the belt type continuously variable transmission of the present application.

  Similar to the region where the thrust ratio is less than 1, in the prior art, the thrust of the low thrust pulley is increased or decreased to ensure a differential thrust corresponding to the target gear ratio, and control to reach the target gear ratio is performed. When the thrust command value on the low thrust side falls below the lower limit thrust, the lower thrust is maintained at the lower limit thrust, and the thrust command of the pulley with high thrust is set to the difference between the thrust command value on the low thrust side and the lower limit thrust to avoid responsiveness deterioration. Add to the value to ensure responsiveness.

  Also in this embodiment, similarly to the region where the thrust ratio is less than 1, the thrust of the low thrust pulley is maintained at the lower slip thrust, and the thrust of the high thrust pulley is increased or decreased to ensure the differential thrust corresponding to the target gear ratio. Control to reach the target gear ratio is performed. If the thrust command value on the high thrust side falls below the lower limit thrust, the thrust command value on the high thrust side is held at the lower limit thrust, and the difference between the thrust command value on the high thrust side and the lower limit thrust is reduced to ensure responsiveness. Add to the thrust command value of the thrust pulley.

(Downshift in areas where the thrust ratio is 1 or more)
When downshifting is performed by increasing the gear ratio from β1 ′ to β2 ′, it is necessary to reduce the belt rotation radius of the primary pulley and increase the belt rotation radius of the secondary pulley.
Similarly to the region where the thrust ratio is 1 or more, in the prior art, in order to achieve downshift by increasing the belt rotation radius of the secondary pulley on the low thrust side, the secondary thrust is increased to correspond to the target gear ratio. Ensure differential thrust and shift speed. At this time, since the primary thrust on the high thrust side remains high, the primary thrust and the secondary thrust are both kept high, and the hydraulic load is high as a whole.

  In this embodiment, in order to achieve downshift by reducing the belt rotation radius in the primary pulley 310 on the high thrust side, the primary thrust F * pri is decreased to ensure the differential thrust corresponding to the target gear ratio. At this time, when the value of the target primary thrust F * pri falls below the slipping lower limit value of the pulley thrust, the primary thrust command value Fpri is held at the slipping lower limit value, and the difference value ΔFp between the slipping limit value and the target primary thrust F * Pri And the difference value ΔFp is added to the secondary thrust command value Fsec.

  Therefore, in the downshift in the region where the thrust ratio is 1 or more, in the prior art, the hydraulic load increases because both the primary thrust and the secondary thrust are kept high, but in this embodiment, the primary thrust command of the high thrust is high. The hydraulic load is reduced by lowering the value Fpri. Further, when the value of the target primary thrust F * pri falls below the slip limit value of the pulley thrust, the primary thrust command value Fpri is held at the slip limit value, and the difference value ΔFp between the slip lower limit value and the target primary thrust F * pri And the difference value ΔFp is added to the secondary thrust command value Fsec to ensure responsiveness.

(Upshift in the area where the thrust ratio is 1 or more)
When performing an upshift by reducing the gear ratio from β1 ′ to β3 ′, it is necessary to increase the belt rotation radius of the primary pulley and reduce the belt rotation radius of the secondary pulley.
Similarly to the region where the thrust ratio is less than 1, in the prior art, the secondary thrust is reduced in order to reduce the belt rotation radius of the secondary pulley on the low thrust side, thereby ensuring a differential thrust corresponding to the target gear ratio, and However, since the secondary thrust corresponding to the target gear ratio β3 is below the slip lower limit, the difference B between the target secondary thrust and the slip lower limit is calculated, and this difference B is used as the primary thrust that is the high thrust side thrust. Add to.

In this embodiment, the secondary thrust, which is the low thrust side pulley thrust, is held at the lower slip thrust, so that the primary thrust F * sec is increased to increase the belt rotation radius of the primary pulley 310 to increase the target gear ratio. The differential thrust corresponding to is secured.
Therefore, in the upshift in the region where the thrust ratio is 1 or more, both the conventional technique and the present embodiment hold the secondary thrust at the lower slip limit and perform the downshift by increasing the primary thrust. As a result, both increase the hydraulic pressure.

[2-2: Contrast of change with time in a region where the thrust ratio is 1 or more]
FIG. 11 is a time chart showing the change over time of each pulley thrust in the prior art and in the present embodiment when downshifting is performed in a region where the thrust ratio RF is 1 or more. FIG. 11A shows a time chart of the prior art, and FIG. 11B shows a time chart of pulley thrust control by the hydraulic control device of the belt type continuously variable transmission of the present application.
The time-dependent changes shown in FIG. 11 correspond to the times t11 to t14 corresponding to the times t1 to t4 in FIG. 9, and the changes in the pulley thrust at each time are upshifts in the region where the actual gear ratio is less than 1 shown in FIG. Since the same change is shown, the description is omitted.

[Effect of this embodiment]
In the prior art, in order to ensure speed change response while avoiding belt slip, a lower limit is set for the pulley thrust so that the belt turning radius of the pulley with low thrust becomes the turning radius corresponding to the target gear ratio. The thrust is calculated to ensure a differential thrust corresponding to the target gear ratio, and when this thrust falls below the lower limit thrust, it is held at the lower limit thrust. Also, in order to avoid the deterioration of responsiveness by reducing the rate of time change of the belt rotation radius of pulleys with low thrust by holding, the difference between thrust and lower limit thrust is taken, and this difference has high thrust Responsiveness was ensured by adding to the thrust command value of the pulley.

  However, in the above prior art, when the upshift is performed in a region where the thrust ratio RF is less than 1, the thrust command value of the secondary pulley that maintains a high thrust remains high, and the thrust of the primary pulley with a lower thrust By increasing the command value, a high hydraulic pressure is required as a whole, which hinders improvement in fuel consumption. In addition, even when downshifting is performed in a region where the thrust ratio RF is 1 or more, the thrust command value of the primary pulley that holds high thrust remains high, and the thrust command value of the secondary pulley that holds lower thrust increases. Therefore, the same problem occurs.

  On the other hand, in this embodiment, in order to reduce the thrust of the pulley on the side where high hydraulic pressure is applied and to secure a differential thrust corresponding to the target gear ratio ip *, the thrust command value of the low thrust pulley is changed to the lower limit thrust. The thrust command value of the high-thrust pulley is lowered while securing the differential thrust corresponding to the target gear ratio, and the gear is shifted. Also, if the thrust command value of the high thrust pulley corresponding to the target gear ratio falls below the slip lower limit thrust, the difference value between the slip lower limit thrust and the thrust command value of the high thrust pulley is taken, and this difference value is the thrust of the low thrust pulley. It was decided to add to the command value.

  Accordingly, when the upshift is performed in a region where the thrust ratio RF is less than 1, the thrust command value of the primary pulley 310 that holds a low thrust is kept low, and the thrust of the secondary pulley 320 that holds a high thrust is reduced. Is possible. Even when downshifting is performed in a region where the thrust ratio RF is 1 or more, the thrust command value of the secondary pulley 320 that holds a low thrust is kept low, while the thrust of the primary pulley 310 that holds a high thrust is reduced. It becomes possible. Therefore, it is possible to provide a hydraulic control device for a belt-type continuously variable transmission that reduces engine load by avoiding unnecessary oil pressure generation while avoiding belt slip and improving fuel efficiency and belt life. (Corresponding to claim 1).

  Also, if the thrust command value of the high thrust pulley corresponding to the target gear ratio falls below the slip lower limit thrust, the difference value between the slip lower limit thrust and the thrust command value of the high thrust pulley is taken, and this difference value is the thrust of the low thrust pulley. By adding to the command value, even when the high thrust pulley is held at the thrust command value, it is possible to ensure responsiveness by increasing the thrust of the low thrust pulley to the minimum necessary. Therefore, it is possible to provide a hydraulic control device for a belt-type continuously variable transmission that avoids belt slip and simultaneously achieves improved fuel efficiency and secures responsiveness (corresponding to claim 2).

Further, the CVT control unit 100 performs control based on detection values of the primary rotation sensor 102, the secondary rotation sensor 103, the throttle opening sensor 105, the engine rotation sensor 104, and the vehicle speed sensor 101. Thereby, control responsiveness can be improved, avoiding belt slip (corresponding to claim 3).
Further, the control unit 100 calculates a differential thrust dF in order to obtain a target shift speed, sets a feedback control amount Ufb to cause the actual speed ratio ip to follow the target speed ratio ip *, and further sets the thrust ratio. The correction value α is calculated in order to equalize the rate of change of RF, and the thrust command values Fpri and Fsec are calculated by the following formulas, so that each control parameter at the time of shift control is assigned a role, and the stability of control is increased. Can be improved.

Fsec = Fs * + Uin, Uin = dF + α · Ufb or Uin = α · (dF + Ufb)
Fpri = Fp * + Uin, Uin == dF + α · Ufb or Uin = α · (dF + Ufb)
Although it is preferable to correct both the feedback control amount Ufb and the differential thrust dF with the correction value α in order to make the rate of change of the thrust ratio RF equal, even if only the feedback control amount Ufb is corrected, a certain effect is obtained. is there.

[Others]
As described above, the best mode for carrying out the present invention has been described based on the embodiment. However, the specific configuration of the present invention is not limited to each embodiment, and the scope of the invention is not deviated. Design changes and the like are included in the present invention.

1 is a system configuration diagram of a vehicle equipped with a CVT hydraulic control apparatus according to an embodiment of the present invention. It is a control block diagram of the CVT control unit of the CVT hydraulic control apparatus of FIG. It is a figure explaining the basic balance thrust concerning CVT oil pressure control of one embodiment of the present invention, (a) is a correlation diagram of thrust with respect to gear ratio and input torque, (b) is a correlation diagram of thrust ratio with respect to gear ratio, (C) is a correlation diagram of the thrust with respect to the gear ratio. It is a correlation diagram of the thrust with respect to the gear ratio explained about the gear ratio and thrust ratio concerning the CVT hydraulic pressure control of one embodiment of the present invention. It is a correlation diagram of the thrust with respect to the gear ratio explaining the basic balance thrust and the control region according to the CVT hydraulic pressure control of one embodiment of the present invention. It is a flowchart which shows the flow of the pulley thrust calculation control process performed in a CVT control unit. It is a flowchart which shows the flow of the hydraulic pressure conversion control process performed in the hydraulic pressure conversion part of a CVT control unit. It is a figure which shows the contrast of the correlation diagram of the thrust with respect to the gear ratio of this prior art and this embodiment in the area | region where thrust ratio is less than 1, (a) shows a prior art, (b) shows this embodiment. It is a time chart which shows a time-dependent change of each pulley thrust in this prior art and this embodiment when performing upshift in a region where the thrust ratio is less than 1, (a) shows the prior art, and (b) shows this embodiment. Indicates. It is a figure which shows the contrast of the correlation diagram of the thrust with respect to the transmission ratio of the prior art and this embodiment in the area | region where a thrust ratio is 1 or more, (a) shows a prior art, (b) shows this embodiment. It is a time chart which shows the time-dependent change of each pulley thrust in this prior art and this embodiment when performing an upshift in a region where the thrust ratio is 1 or more, (a) shows the prior art, (b) shows this embodiment. Indicates.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 20 Torque converter 30 Forward / reverse clutch 40 Oil pump 51 1st pressure regulation valve 52 2nd pressure regulation valve 71 Primary pressure regulation valve 72 Secondary pressure regulation valve 100 Control unit 101 Vehicle speed sensor 102 Primary rotation sensor 103 Secondary rotation sensor 104 Engine rotation sensor 105 Throttle Opening sensor 108 Primary solenoid 109 Secondary solenoid 106 Hydraulic pressure conversion unit 107 Current conversion unit 200 Transmission ratio control unit 201 Target transmission ratio calculation unit 202 Actual transmission ratio calculation unit 203 Input torque calculation unit 204 Slip lower limit thrust calculation unit 205 Thrust ratio calculation unit 206 Basic balance thrust calculation unit 207 Difference thrust calculation unit 208 Correction value calculation unit 209 Shift feedback control unit (shift feedback amount calculation unit)
210 Anti-slip and hydraulic minimum thrust distribution calculation unit (hereinafter referred to as thrust distribution calculation unit)
310 Primary pulley 311 Primary slide pulley 320 Secondary pulley 321 Secondary slide pulley

Claims (6)

A belt-type continuously variable vehicle for a vehicle in which a driving pulley and a driven pulley are connected by a belt, and the rotational radius of the belt in both pulleys is changed by adjusting a hydraulic thrust applied to both pulleys, thereby adjusting a gear ratio. A hydraulic control device for a transmission,
A hydraulic actuator that changes the rotational radius of the driving pulley and the driven pulley according to the hydraulic thrust; and
Vehicle information detection means for detecting vehicle information;
A control unit that calculates the hydraulic thrust for the driving pulley and the driven pulley based on the vehicle information detected by the vehicle information detecting means, and controls the hydraulic actuator based on the calculated value. ,
The control unit is
A target gear ratio is calculated based on the vehicle information, a thrust ratio that is a ratio of a hydraulic thrust force to the driving pulley and a hydraulic thrust force to the driven pulley for maintaining the target gear ratio is calculated, and the driving A driving-side slip lower limit value and a driven-side slip lower limit value, which are lower limit values of hydraulic thrust at which the belt does not slip with respect to rotation of the side pulley and the driven pulley,
When the thrust ratio is less than 1, the drive-side slip lower limit value is set to a first drive-side target hydraulic thrust that is a target hydraulic thrust of the drive-side pulley, and the drive-side slip lower limit value and the target gear ratio A first driven target hydraulic thrust that is a target hydraulic thrust of the driven pulley is calculated based on
When the thrust ratio is 1 or more, the driven side slip lower limit value is set to a second driven side target hydraulic thrust that is a target hydraulic thrust of the driven pulley, and the driven side slip lower limit value and the target speed change ratio are set. And calculating a second drive-side target hydraulic thrust that is a target hydraulic thrust of the drive-side pulley ,
Further, when the hydraulic thrust ratio is less than 1, a value obtained by adding or subtracting a control thrust amount required at the time of shifting to a driven side basic balance thrust, which is a hydraulic thrust of the driven pulley for maintaining the target speed ratio. The first driven-side target hydraulic thrust candidate value is calculated as a candidate value of the first driven-side target hydraulic thrust, the driven-side slip lower limit value is compared with the first driven-side target hydraulic thrust candidate value, and the first driven-side target hydraulic thrust candidate value is When it is larger than the side slip lower limit value, the first driven side target hydraulic thrust candidate value is set as the first driven target hydraulic pressure thrust, and the driven side slip lower limit value is larger than the first driven side target hydraulic thrust candidate value. In this case, a driven side differential value that is a difference between the driven side slip lower limit value and the first driven side target hydraulic thrust candidate value is calculated, and the sum of the drive side slip lower limit value and the driven side differential value is calculated as the first value. 1 drive side target hydraulic thrust and Rutomoni, the driven side slip limit value and the first driven side target hydraulic thrust,
When the hydraulic thrust ratio is 1 or more, a value obtained by adding or subtracting a control thrust amount necessary for shifting to the driving side basic balance thrust, which is the hydraulic thrust of the driving pulley for maintaining the target speed ratio, is the first value. 2 is calculated as a candidate value for the drive-side target hydraulic thrust, the drive-side slip lower limit value is compared with the second drive-side target hydraulic thrust candidate value, and the second drive-side target hydraulic thrust candidate value is compared with the drive-side slip When larger than the lower limit value, the second drive side target hydraulic thrust candidate value is set as the second drive side target hydraulic pressure, and when the drive side slip lower limit value is larger than the second drive side target hydraulic thrust candidate value, A drive-side differential value, which is a difference between the drive-side slip lower limit value and the second drive-side target hydraulic thrust candidate value, is calculated, the drive-side slip lower limit value is set as the second drive-side target hydraulic thrust, and the driven Side slip lower limit The sum of the driving-side difference value, characterized in that said second driven-side target hydraulic thrust, the hydraulic control device for a vehicular belt-type continuously variable transmission. The vehicle information detecting means, an engine rotation sensor, the drive-side rotation sensor, the driven-side rotation sensor, a throttle opening sensor, and characterized in that it is a car speed sensor, a vehicle belt type continuously variable transmission according to claim 1, wherein Hydraulic control device for the machine. The control unit is
In order to obtain a target shift speed, a differential thrust that is a difference between a hydraulic thrust for the driving pulley and a hydraulic thrust for the driven pulley is calculated,
The difference between the target stroke displacement of the driven pulley calculated from the target gear ratio and the actual stroke displacement of the driven pulley calculated from the actual gear ratio to cause the actual gear ratio to follow the target gear ratio. Based on the stroke difference value and the feedback control gain, the feedback control amount applied to the hydraulic thrust is calculated,
The hydraulic actuator is controlled based on a hydraulic thrust obtained by correcting the first or second drive side target hydraulic thrust and the first or second driven side target hydraulic thrust by the differential thrust and the feedback control amount. The hydraulic control device for a belt-type continuously variable transmission for a vehicle according to claim 1 or 2 , characterized by the above. The control unit is
Based on the drive-side slip lower limit value and the driven-side slip lower limit value, a correction value for equalizing the change rate of the thrust ratio is calculated, and the feedback control amount is corrected by the correction value, and then the hydraulic pressure 4. The hydraulic control device for a vehicle belt-type continuously variable transmission according to claim 3 , wherein the actuator is controlled. The control unit is
Based on the driving-side slip lower limit value and the driven-side slip lower limit value, a correction value for equalizing the change rate of the thrust ratio is calculated, and the differential thrust and the feedback control amount are respectively corrected by the correction value. The hydraulic control device for a vehicle belt type continuously variable transmission according to claim 3 , wherein the hydraulic actuator is controlled. The correction value for equalizing the rate of change of the thrust ratio is obtained by calculating the drive side slip lower limit value and the driven side slip lower limit value from the hydraulic thrust at which the drive side base balance thrust and the drive side base balance thrust match. 6. The belt-type continuously variable transmission for a vehicle according to claim 4 or 5 , characterized in that the transmission gear ratio at which the stroke displacement of each pulley is neutral is made dimensionless by using a hydraulic thrust between a slip lower limit value of 1. Hydraulic control device for the machine.

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